The overall objectives of this research project are to decipher the pathway(s) of procollagen biosynthesis and processing, from the polyribosomal level to the final product, the extracellular fibrils. Such a comprehensive analysis is made possible by growing cells in culture, especially mutant cells which may accumulate intermediate forms of procollagen at various stages in the processing pathway. This approach should also enable us to characterize the defects in diseased tissues which produce collagen molecules either of abnormal size, or incorrectly processed, or of unsuitable genetic type.